HORMONAL ACTIVITY OF THE THYROID-GLAND IN PATIENTS WITH PAROXYSMAL SUPRAVENTRICULAR TACHYARRHYTHMIAS

In order to investigate hormonal function of the thyroid gland In supr abentricular tachyarrhythmia 4 groups of patients were studied. Group 1 comprised patients with supraventricular tachycardias and syndromes of ventricular preexcitation; group 2 - patients with Wolff - Parkinso n - White phenomenon; group 3 - patients with atrioventricular nodal t achycardia and cardiosclerosis after myocarditis; group a - patients w ith ischemic heart disease and Wolf - Parkinson - White syndrome, Leve ls of thyroid hormones were determined at sinus rhythm, during spontan eous and pacing-induced attacks of tachycardia, and during acute and c hronic pharmacological testing of metoprolol and disopyramide. The hig hest levels of triiodothyronine and thyroxine were, observed in patien ts with ventricular preexcitation without coronary [athology. An incre ase in concentration of thyroxine was significant (p<0.01) in patients with functioning accessory conduction pathways (group 1). Spontaneous attach was accompanied by elevation of levels of thyroid hormones. Th is confirmed difference of trigger mechanisms of spontaneous and pacin g-induced tachycardia. Chronic metoprolol use lowered levels of triiod othyronine and thyroxine, while therapy with disopyramide was associat ed with a tendency to increase in concentration of these hormones.